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Editorials

Poor vision and falls

BMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c2456 (Published 25 May 2010) Cite this as: BMJ 2010;340:c2456
  1. A John Campbell, professor of geriatric medicine,
  2. Gordon Sanderson, associate professor and optometrist,
  3. M Clare Robertson, research associate professor
  1. 1Department of Medical and Surgical Sciences, Dunedin School of Medicine, Dunedin, 9016, New Zealand
  1. john.campbell{at}otago.ac.nz

    Correcting vision can help, but do so with care

    Improving the vision of an older person should lower the likelihood of a fall. Randomised controlled trials suggest that this is often true, but not always.1 In fact, well meaning interventions can increase the risk of falls and changes should be made with care.

    Poor vision increases the risk of falling.2 The person with impaired vision may not see hazards, particularly if peripheral vision is limited; may not see the poorly lit bottom step, particularly if depth perception is affected; and may not notice the change from carpet to slippery tiles, particularly if contrast sensitivity is impaired.

    Multifocal and bifocal glasses further impair contrast sensitivity and depth perception.3 Multifocals also cause loss of acuity in the lower peripheral visual field owing to astigmatic aberration. Protective responses, such as grabbing a rail, may also be hindered by the peripheral prismatic effect. Use of these lenses is associated with an increased risk of falling.

    In the linked randomised controlled trial (doi:10.1136/bmj.c2265), Haran and colleagues assess whether providing single lens distance glasses to regular users of multifocal glasses lowers the rate of falls.4 It did by around 40% in people who regularly took part in outside activities (incidence rate ratio 0.60, 95% CI 0.42 to 0.87). In frailer people, who spent more time inside, no significant difference was seen in falls inside and a significant increase was seen in falls outside. The overall fall rate in the intervention group was not reduced.

    It is important to check vision and glasses in an elderly person who presents after a fall. More active patients may benefit from changing multifocal glasses to single focus glasses for walking and standing activities. Prescription of new lenses should also involve careful instruction in their use. This was an important part of the trial intervention. In another trial, assessment of vision and prescription of new glasses significantly increased falls in the intervention group.5 One of the reasons suggested for this was the difficulty older people may have adjusting to sudden change in vision.

    Participants in Haran and colleagues’ study were encouraged to have transition (photochromic) single focus lenses, which become darker in bright sunlight. This would have decreased glare, particularly in those with early cataracts, and may have been important in those who were active outside. Some trial participants had distance glasses with a fixed or graduated tint. If worn inside, these would have reduced visual acuity and may have increased the risk of falling. Although the tints in photochromic lenses lighten when removed from an ultraviolet source, the transition time can be up to two minutes. During this time the lenses are, in effect, still tinted. Older people should be advised against fixed tint glasses and should be aware of the delayed change with some photochromic lenses.

    After correction of refractive errors, cataract is the most common correctable cause of impaired vision in older people. First eye cataract surgery decreases the rate of falls and improves activity, mood, confidence, and visual handicap. A randomised controlled trial showed a 34% reduction in falls for people who had cataract surgery compared with controls on the waiting list.6 Another trial of second eye surgery found a similar but non-significant reduction in falls.7 Most of the reduction in falls possibly comes with improved sight in one eye. However, having normal sight in two eyes would improve depth perception, contrast sensitivity, and peripheral vision, which are all important for safe walking.

    Intraocular lenses that correct astigmatism (toric lenses) make emmetropia a reasonable expectation. A distance correction means that bifocals are no longer needed, which lowers the risk of falling.

    A randomised controlled trial of fall prevention in people with severely impaired vision has shown that falls can still be prevented.8 Assessment and advice from an occupational therapist reduced falls by 60% when this was the sole intervention and, unexpectedly, by a lesser amount when an exercise programme was also provided. Both outside and inside falls were reduced by the same amount, and falls were reduced whether or not home hazards were removed.9 Individual advice on safe activity by a trained occupational therapist is most important for people with severe loss of sight.

    We can learn from both the expected and the unexpected results of these studies. Maintaining optimum vision is best done by regular eye assessments so that the older person does not have to adapt to major changes in lenses. Although many factors other than visual impairment may contribute to the risk of falling, change should be introduced step by step in a planned manner so that the person is not overwhelmed. A person’s propensity to fall should be considered when determining priority on a cataract waiting list. Doctors should consider vision and glasses, optometrists should consider the risk of falls, and good communication between the two will certainly help.

    Notes

    Cite this as: BMJ 2010;340:c2456

    Footnotes

    • Research, doi:10.1136/bmj.c2265
    • Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: (1) They have had support from the University of Otago for the submitted work; (2) They have had no relationships with any company that might have an interest in the submitted work; (3) They have no spouses, partners, or children with financial relationships that may be relevant to the submitted work; and (4) They have no non-financial interests that may be relevant to the submitted work.

    • Provenance and peer review: Commissioned; not externally peer reviewed.

    References

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